Apparatus for strengthening weak electrical currents.



v A. POLLAK. APPARATUS FOR STRENGTHENING WEAK ELEGTRIGAL GUBRENTS. APPLICATION FILED AUG. 7, 1908. 939,625, 7 Patented Nov. 9, 1909.

INVENTOR N i .V 7/

WITNESSES:

v M L w l/ j bot-h coils.

' To all whom 'it may concern:

UNITED STATES PATENT OFFICE.

ANTON POLLAK, or rARrs; FRANCE.

APPARATUS FOR STRENGTHENING WEAK ELECTRICAL CURRENTS.

Application filed August 7, 1908. Serial No. 447,422.

Be it known that I, ANTON PoLLAK, a. subject of the King of Hungary, residing in Paris, France, have invented certain new and useful Improvements in Apparatus for Strengthening \Veak Electrical Currents, of which the following is a specification.

The object of the invention is to provide an apparatus for the strengthening of weak current impulses, such for example as telephone currents. This has been accomplished heretofore by introducing into a magnetic field a movable coreless coil attached to a membrane of a microphone, or to any similar part of a carbon contact or thelike.

According to the present invention the operation of apparatus working on this principle is improved by passing'the microphone circuit of such a coil through a second strengthening coil, using a single magnet for The air space for the two coils is preferably provided by the use of a magnet shell which is separate from the core of the magnet, and by leaving at both ends of the magnet core a narrow space for the coils. In this way an apparatus is provided in which each of the two poles of the one magnet is used as a strengthener without the action of one being injuriously affected by that of the other; these two poles being arranged opposite eachother on the longitudinal axis of the magnet. \Vith this arrangement the apparatus is made extremely simple, a higher efliciency is obtained than with revious apparatus, and the cost of manufacture is small.

The accompanying drawings illustrate an embodiment of the invention.

Figure 1 is a vertical section of an apparatus showing also the electrical connections of the two strengthening coils; Fig. 2 is a plan partly in section of the apparatus, the microphone membrane being removed.

Referring to the embodiment of the invention illustrated, the electro-magnet consists of a shell 6, a core 7, and an exciting coil 18. .Plates 8 of non-magnetic material serve for fastening the core 7 in the shell.

The upper and lower'end plates'l of the shell 6 of the electro-magnet are rovided with circular openings 19 in whic lie the ends of the core 7 anarrow annular intermediate space being left on each end between the core 7 and the edge of the side opening. In each' of these spaces'is a .coil 2 Specification of Letters Patent.

tion a magnet having Patented Nov. 9, 1909.

through which passes the current to be strengthened. The'c'oils 2 are mounted on elastic arms 3 in such a way that they can move only in the direction of their-longitudinal axis. Each coil 2 is attached by arms'A to a membrane 5 of a microphone;

the upper coil to themicrophone 10 and the lower coil to, the microphone 14, which microphones are in the circuits of batteries 11 and 15 respectively. One of the coils 2, for

example the upper one, is connected with the line wires 9, and, the opposite coil is in the circuit'of the-microphone 10 of the first coil;

so that the movement of the upper coil 2 caused by the line current causes fluctuations of the current in the lower coil by means of the microphone 10, the transformer 12 and the wires 13. The lower coil 2 acts and then conveyed to the telephone.

Though I'hav'e described'with great particularity of detail a specific practical apparatus embodying the invention, yet it is not to be understood therefrom that the invention is restricted to the ratus shown and described. Various modi fications thereof may be made b those skilled in the art without departing fi omthe invention.

The apparatus can be advantageously used in telephone circuits as a sound strengthener. It can also be advantageously employed in telegraphic systems where the current which actuates the receiver is very weak (cable, for the strengthening of the current.

What I claim is -1. apparatus for the strengthening of weak electrlc currents,

plates and a core with two ends between which and the end plates there is a narrow said air spaces air space, a coil in each of supported movably in the was only, a microphone. actuated by each of said coils, one of said coils carrying the current to be strengthened and the other coil be.- ing in the circuit of the first coil. I 2. An apparatus for the stren henin of weak electric currents, including 111 combinadirection of its including in combinaa shell with two end microphone of the the upparticular appatelegraph, wireless telegraphy, &c.)

I tion a magnet having a shell 6 with opposite -ape1'tured end plates 1, and having a core 7 tween the core and the end plates, coils 2 in 1 l l In witness whereof, I have hereunto signed my name 111 the presence of two sub- 13 scribing wltnesses.

with its opposite ends lying in the apertures of said end plates with narrow air spaces be- ANTON POLLAK.

\Vitnesses:

H. C. COKE, JACK H. BAKER.

said air spaces and supported movably in their axial direction, and microphones attached to said coils. 

